Surviving Invasion: Regaining Native Fish Resilience Following Fish Invasions in a Modified Floodplain Landscape

• Published in: Water resources research 2021-09, Vol.57 (9), p.n/a
• Main Authors: Pingram, M. A., Collier, K. J., Williams, A. K., David, B. O., Garrett‐Walker, J., Górski, K., Özkundakci, D., Ryan, E. F.
• Format: Article
• Language: English
• Subjects: Agricultural development; Aquatic communities; Aquatic ecosystems; Biodiversity; Biological settlement; Catchment area; Climate change; Control theory; Ecological adaptation; Ecological effects; Ecosystem services; Ecosystems; Environmental quality; Environmental restoration; Feedback loops; Fish; Fish populations; Fisheries; Flood control; flood management; Flood plain management; floodplain resilience; Floodplains; Floods; Habitats; Hot spots; Human settlements; Hydrology; Indigenous species; Infrastructure; Introduced species; invasive alien fish; Invasive fish; Invasive species; Land settlement; Landscape; Levees; native fisheries; Native organisms; Native species; Nonnative species; Proliferation; Resilience; Restoration; Rivers; Strands; Survival; Threatened species; Urban agriculture; Urban sprawl; Water quality
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2020WR029513

Floodplain ecosystems are focal points for human settlement, and consequently are often subjected to extensive modification and infrastructure development. Establishment of non‐native species in floodscapes presents a range of challenges when they become problematic and drive changes in native aquatic communities and ecosystems. These non‐native species are often tolerant of reduced water and habitat quality, conferring a competitive advantage over native species. The coupled effects of invasive alien species, landscape modification and floodscape hydrological control collectively reduce ecological resilience, creating feedback loops that reinforce negative effects on native fish. The regulated lower Waikato River floodplain is a New Zealand hotspot for fish introductions, with their proliferation exacerbating the effects of agricultural development, urban expansion, and flood control infrastructure. We argue that the resilience of native fish assemblages to these pressures can be improved through utilizing a series of complementary measures, including enhanced catchment management, strategic alterations to the location, design, and operation of floodplain infrastructure (e.g., gates, pumpstations, and stopbanks), habitat restoration for native fish, and targeted management of invasive species. These measures will need to consider the likely persistence of invasive alien fish, however, to limit their expansion in the face of a changing climate. Although knowledge and implementation gaps exist, tying these strands together presents an opportunity to enhance the resilience of native fisheries into the future. Key to success will be re‐thinking floodplain management to include ecosystem services, and this will require ongoing commitment and cooperation amongst all stakeholders to address knowledge gaps and enable effective implementation. Plain Language Summary River floodplains are important areas for human settlement, and as a result have been modified for urban, agricultural, and other infrastructure development. Associated water and habitat quality declines aid the proliferation of non‐native species in these vulnerable ecosystems, and contribute to further impacts on native biodiversity. Here, we discuss the ecological consequences of the combined effects of invasive alien fish species, landscape modification and flood control infrastructure in the context of the Waikato River floodplain, New Zealand, which is a hotspot for fish introductions. We explore